A. Field of Invention
The present invention relates to a microfluidic device which comprises two or more microchannel structures (e.g., set 1, set 2, set 3), each of which comprises one or more inlet ports, one or more outlet ports, and a structural unit which is located between an inlet port and an outlet port. The structural unit comprises one or more inlet microconduits, each of which communicates with an inlet port, and an outlet microconduit, which communicates with an outlet port, and an microcavity, which is located between said inlet port and said outlet port. More particularly, the structural unit starts at the inlet ends of the inlet microconduits and ends at the outlet end of the outlet microconduit and includes valves and anti-wicking means that may be present at the end parts.
B. Related Art
Typically, microfluidic devices that comprise the above-mentioned structural unit have not comprised any means that will secure parallelity with a low inter-channel variation in flow rate between individual microchannel structures. The residence time for reactants within the individual microcavities and elsewhere in the microchannel structures has typically varied in an unintended manner within wide limits. Depending on kind of reactants, for instance, this may heavily influence the results obtained.
Magnus Gustavsson et al., (Gyros AB) have presented experiments comprising parallel reaction (adsorption) in a microfluidic device (“Integrated sample preparation and MALDI MS on a microfluidic compact disc (CD with improved sensitivity”, ASMS 2001). This presentation described a MALDI MS integrated microfluidic affinity system based on adsorbing a protein digest to a reverse phase matrix and subsequent desorption and transport of peptides to a combined outlet port/MALDI MS target. The demands on reproducibility in binding, the control of liquid flow rate, and the residence time were low. Harrison et al., (WO 0138865, University of Alberta) have described a solid phase extraction method in a singular microchannel structure by affinity binding under flow conditions. Eteshola et al., (Sensors and Actuators B 72 (2001) 129–133), Sato et al., (Anal. Chem. 72 (2000) 1144–1147); and Mian et al., (WO 9721090, Gamera Biosciences), for instance, have described performing affinity reactions under non-flow conditions in microcavities.
The use of centrifugal force for moving liquids within microfluidic systems has also been described for instance by Abaxis Inc (WO 9533986, WO 9506870, U.S. Pat. No. 5,472,603); Molecular devices (U.S. Pat. No. 5,160,702); Gamera Biosciences/Tecan (WO 9721090, WO 9807019, WO 9853311), WO 01877486, WO 0187487; Gyros AB/Amersham Pharmacia Biotech (WO 9955827, WO 9958245, WO 0025921, WO 0040750, WO 0056808, WO 0062042, WO 0102737, WO 0146465, WO 0147637, WO 0147638, WO 0154810, WO 0241997, WO 0241998, PCT/SE02/00531, PCT/SE02/00537, PCT/SE02/00538, PCT/SE02/00539 and PCT/SE02/01539. See also presentations made by Gyros AB at various scientific meetings: High-through put screening SNP scoring in microfabricated device, Nigel Tooke (September 99); Microfluidics in a rotating CD (Ekstrand et al.) MicroTAS 2000, Enschede, The Netherlands, May 14–18, 2000; SNP scoring in a disposable microfabricated CD device (Eckersten et al.) and SNP scoring in a disposable microfabricated CD device combined with solid phase Pyrosequencing™ (Tooke et al.) Human Genome Meeting, HGM 2000, Vancouver, Canada, Apr. 9–12, 2000; and Integrated sample preparation and MALDI MS on a microfluidic compact disc (CD with improved sensitivity (Magnus Gustavsson et al.) ASMS 2001 (spring 2001).
The publications above in the name Gyros AB or Amesham Pharmacia Biotech primarily concerns nl-volumes and problems associated therewith while the other publications primarily aims at μl-volumes or larger.